The objective of this study is to delineate the dynamic aspects of the micro-circulation of the rat testes and epididymis utilizing intravitalmicroscopy. Previous studies concerning testicular/epididymal microvasculature have been limited to static casting techniques, and as such have not studied the dynamics of testicular and epididymal blood flow. Topographic, hemodynamic and permeability studies will be carried out utilizing intravital microscopic techniques. Thereafter, the effect of a surgically created varicocele will be studied in the acute and chronic states in the respect to the above parameters. This will be performed in both juvenile and adult animals. It is hypothesized that alterations in microvascular function resulting from the pathologic state of the varicocele result in the observed altered spermatogenic and epididymal function. Presently, the varicocele is thought to be the leading identifiable cause of male infertility; however, little understanding of its pathophyiology exists. Until a greater understanding of the microvasculature of the normal testicle and epididymis is obtained, the impact of the gross vascular lesion as represented by the varicocele cannot be understood.